App Proxy returns 404 — Shopify never makes the request to my proxy URL

Dev Platform
1

What I’ve tried:

  1. Cloudflare Tunnel pointing to my Next.js app — 404
  2. Cloudflare Worker (publicly accessible, no tunnel) — 404
  3. Hitting the proxy URL directly (curl https://my-worker.workers.dev/) returns a valid JSON response, so the endpoint is definitely up and reachable
  4. Running wrangler tail on the worker while visiting the store URL — zero requests come through. Shopify is not forwarding the request at all.
  5. Uninstalled and reinstalled the app on the dev store
  6. Ran shopify app dev to sync the config

My config (shopify.app.development.toml):

client_id = "d6d08…"
name = "My App (Dev)"
application_url = "https://my-worker.workers.dev"
embedded = true

[access_scopes]
scopes = "read_customers,write_app_proxy,write_customers"
use_legacy_install_flow = true

[app_proxy]
url = "https://my-worker.workers.dev"
subpath = "endpoint"
prefix = “apps”

What shopify app dev shows:

app_proxy │ Using URL: https://my-worker.workers.dev
app_proxy │ Any changes to prefix and subpath will only apply to new installs

Environment:

  • Development store
  • Custom app (no Remix, no Shopify app template)
  • Shopify CLI latest
  • API version 2026-01

The 404 is coming from Shopify itself, not my backend. It seems like the app proxy is either not being registered on the store or Shopify is not routing /apps/endpoint to my proxy URL at all.

Has anyone else experienced this? Is there a step I’m missing to activate the app proxy on an existing install? Does the app need to be reinstalled for proxy config changes to take effect?

Screenshot 2026-02-01 at 17.34.20
Screenshot 2026-02-01 at 17.34.20956×1004 23.2 KB

2

Did you double check the proxy config in Admin? If you previously registered it under a different route, or if there was another app w/ a conflicting path, the proxy may be under a different subpath.

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3

Yep it matches exactly the same, I’ve only used the one path since adding it.

Its a fresh/new development store, no other apps installed.

4

Is this a problem during local/development or something? It just seems Shopify doesn’t ever hit my endpoint at all :thinking:

5

Any more ideas here @NickWesselman ?

6

Any errors I’ve seen are do not surface Shopify 404s, they usually return something like “There was an error in the third-party application.” if it’s 5xx error while still being in the theme layout on the frontend. Or if the end URL is accessible (non 5xx) it should still open the url, just show you the 404 or any errors from the external service.
I think this maybe a bug.

7

So I have absolutely no idea what was happening but this has resolved itself..classic.

No longer getting a redirect and 404..

8

Hey, can you retry uninstall and reinstall the app. While same app (staging/prod) is installed in other stores. Then proxy url is incremented automatically and break things. I just noticed this in my store.

9

The post has already been resolved.

10

I had a similar issue. Upgrading the Shopify CLI version from 3.93 to 3.94 fixed it for me